HP 50g: Neighbour Function (Dedekind Cut) Programme Challenge

[pier4r]

(09-27-2017 11:51 AM)Joe Horn Wrote:  Sorry, but I don't understand your question. The only thing that Y does is tell NEIGHBOR which direction to go. If Y>X, then NEIGHBOR(X,Y) returns the very next number GREATER than X which the HP-71 is capable of representing, and if Y<X then it returns the very next number LESS than X. The phrase "machine-representable number" means "limited to a 12-digit mantissa". The function has nothing to do with strings.

Examples:
NEIGHBOR(6,9) --> 6.00000000001 (the nearest machine-representable number above 6)
NEIGHBOR(6,2) --> 5.99999999999 (the nearest machine-representable number below 6)

Ah, ok, then I misunderstood. I thought the right function was like 'Y' is not representable by the system, can you give the closer number to Y, starting from X, that can represent Y?